prevent taking from empty foundation

[solVItaire.git] / sol.c

#define _DEFAULT_SOURCE /* for getopt, sigaction, usleep */
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <time.h>
#include <termios.h>
#include <unistd.h>

#include "sol.h"
#include "schemes.h"

struct playfield f;
struct opts op;

// action table {{{
/* stores a function pointer for every takeable action; called by game loop */
int (*action[NUM_PLACES][10])(int,int,int) = {
#ifdef KLONDIKE
        /* 1    2    3    4    5    6    7   stk  wst  fnd*/
/* 1 */ { t2f, t2t, t2t, t2t, t2t, t2t, t2t, nop, nop, t2f },
/* 2 */ { t2t, t2f, t2t, t2t, t2t, t2t, t2t, nop, nop, t2f },
/* 3 */ { t2t, t2t, t2f, t2t, t2t, t2t, t2t, nop, nop, t2f },
/* 4 */ { t2t, t2t, t2t, t2f, t2t, t2t, t2t, nop, nop, t2f },
/* 5 */ { t2t, t2t, t2t, t2t, t2f, t2t, t2t, nop, nop, t2f },
/* 6 */ { t2t, t2t, t2t, t2t, t2t, t2f, t2t, nop, nop, t2f },
/* 7 */ { t2t, t2t, t2t, t2t, t2t, t2t, t2f, nop, nop, t2f },
/*stk*/ { nop, nop, nop, nop, nop, nop, nop, nop, s2w, nop },
/*wst*/ { w2t, w2t, w2t, w2t, w2t, w2t, w2t, w2s, w2f, w2f },
/*fnd*/ { f2t, f2t, f2t, f2t, f2t, f2t, f2t, nop, nop, nop },
#elif defined SPIDER
        /* 1    2    3    4    5    6    7    8    9    10*/
/* 1 */ { t2f, t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2t },
/* 2 */ { t2t, t2f, t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2t },
/* 3 */ { t2t, t2t, t2f, t2t, t2t, t2t, t2t, t2t, t2t, t2t },
/* 4 */ { t2t, t2t, t2t, t2f, t2t, t2t, t2t, t2t, t2t, t2t },
/* 5 */ { t2t, t2t, t2t, t2t, t2f, t2t, t2t, t2t, t2t, t2t },
/* 6 */ { t2t, t2t, t2t, t2t, t2t, t2f, t2t, t2t, t2t, t2t },
/* 7 */ { t2t, t2t, t2t, t2t, t2t, t2t, t2f, t2t, t2t, t2t },
/* 8 */ { t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2f, t2t, t2t },
/* 9 */ { t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2f, t2t },
/*10 */ { t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2f },
/*stk*/ { s2t, s2t, s2t, s2t, s2t, s2t, s2t, s2t, s2t, s2t },
#elif defined FREECELL
        /* 1    2    3    4    5    6    7    8   cll  fnd*/
/* 1 */ { t2f, t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2c, t2f },
/* 2 */ { t2t, t2f, t2t, t2t, t2t, t2t, t2t, t2t, t2c, t2f },
/* 3 */ { t2t, t2t, t2f, t2t, t2t, t2t, t2t, t2t, t2c, t2f },
/* 4 */ { t2t, t2t, t2t, t2f, t2t, t2t, t2t, t2t, t2c, t2f },
/* 5 */ { t2t, t2t, t2t, t2t, t2f, t2t, t2t, t2t, t2c, t2f },
/* 6 */ { t2t, t2t, t2t, t2t, t2t, t2f, t2t, t2t, t2c, t2f },
/* 7 */ { t2t, t2t, t2t, t2t, t2t, t2t, t2f, t2t, t2c, t2f },
/* 8 */ { t2t, t2t, t2t, t2t, t2t, t2t, t2t, t2f, t2c, t2f },
/*cll*/ { c2t, c2t, c2t, c2t, c2t, c2t, c2t, c2t, c2f, c2f },
/*fnd*/ { f2t, f2t, f2t, f2t, f2t, f2t, f2t, f2t, f2c, nop },
#endif
};
// }}}

// argv parsing, game loops, cleanup {{{
int main(int argc, char** argv) {
        /* opinionated defaults: */
        op.s = &unicode_large_color;
        op.v = 1; /* enable fake visbell by default */
#ifdef SPIDER
        op.m = MEDIUM;
#endif

        int optget;
        opterr = 0; /* don't print message on unrecognized option */
        while ((optget = getopt (argc, argv, "+:hs:vbcmMV")) != -1) {
                switch (optget) {
#ifdef SPIDER
                case 's': /* number of suits */
                        switch (optarg[0]) {
                        case '1': op.m = EASY; break;
                        case '2': op.m = MEDIUM; break;
                        case '4': op.m = NORMAL; break;
                        default: goto error;
                        } break;
#endif
                case 'b': op.s = &unicode_large_mono; break;
                case 'c': op.s = &unicode_large_color; break;
                case 'm': op.s = &unicode_small_mono; break; /* "mini, monochrome" */
                case 'M': op.s = &unicode_small_color; break; /* "mini, colorful" */
                case 'V': op.v = 0; break; /* WARN: experimental; might change */
                case 'h': default: goto error;
                error:
                        fprintf (stderr, SHORTHELP LONGHELP KEYHELP, argv[0]);
                        return optget != 'h';
                }
        }

        signal_setup();
        atexit (*quit);

        signal_handler(SIGWINCH); /* initialize window size */

newgame:
        screen_setup(1);

        switch(sol()) {
        case GAME_NEW: goto newgame;
        case GAME_WON:
                print_table(NO_HI, NO_HI);
                win_anim();
                if (getch(NULL)=='q') return 0;
                goto newgame;
        case GAME_QUIT: return 0;
        }
}

#define is_tableu(where) (where <= TAB_MAX) /* "card games helper functions" */

int sol(void) {
        long seed = time(NULL);
restart:
        free_undo(f.u);
        deal(seed);

        int from, to, opt;
        int ret;
        for(;;) {
                switch (get_cmd(&from, &to, &opt)) {
                case CMD_MOVE:
                        ret = action[from][to](from,to,opt);
#ifdef FREECELL
                        if (ret == ERR && is_tableu(from) && to == from)
                                /* t2f failed? try t2c! */
                                ret = t2c(from, STOCK, 0);
#endif
#ifdef INVERSE_MOVE
                        if (ret == ERR && is_tableu(from) && is_tableu(to))
                                /* try again with from/to swapped: */
                                ret = action[to][from](to,from,opt);
#endif
                        switch (ret) {
                        case OK:  break;
                        case ERR: visbell(); break;
                        case WON: return GAME_WON;
                        }
                        break;
                case CMD_JOIN:
                        switch (join(to)) {
                        case OK:  break;
                        case ERR: visbell(); break;
                        case WON: return GAME_WON;
                        }
                        break;
                case CMD_HINT:  break;//TODO: show a possible (and sensible) move. if possible, involve active cursor
                case CMD_FIND:
                        f.h[0] = getchar(); /* NOTE: not using getch(), so f,esc clears hls */
                        f.h[1] = '\0';
                        break;
                case CMD_SEARCH:
                        raw_mode(0);
                        printf("\r/"); fflush(stdout);
                        fgets(f.h, 3, stdin);
                        if (f.h[0] != '\n' && f.h[1] != '\n') while(getchar()!='\n'); // note: when we read 1 byte, it is followed by CR, NUL. if we read two bytes (or more), it is only followed by NUL, since there is no space for the CR. TODO: cleanup
                        raw_mode(1);
                        f.h[2] = '\0';
                        break;
                case CMD_UNDO:  undo_pop(f.u); break;
                case CMD_INVAL: visbell(); break;
                case CMD_NEW:   return GAME_NEW;
                case CMD_AGAIN: goto restart;
                case CMD_QUIT:  return GAME_QUIT;
                case CMD_HELP:
                        printf (KEYHELP "\nPress any key to continue.");
                        getch(NULL);
                        break;
                }
        }
}

void quit(void) {
        screen_setup(0);
        free_undo(f.u);
}
//}}}

// card games helper functions {{{
#define get_suit(card) \
        ((card-1) % NUM_SUITS)
#define get_rank(card) \
        ((card-1) / NUM_SUITS)
#define get_color(card) \
        ((get_suit(card) ^ get_suit(card)>>1) & 1)

int find_top(card_t* pile) {
        int i;
        for(i=PILE_SIZE-1; i>=0 && !pile[i]; i--);
        return i;
}
int first_movable(card_t* pile) {
        /* NOTE: in FREECELL this does not take max_move into account! */
        int i = 0;
        for (;pile[i] && !is_movable(pile, i); i++);
        return i;
}
int turn_over(card_t* pile) {
        int top = find_top(pile);
        if (pile[top] < 0) {
                pile[top] *= -1;
                return 1;
        } else return 0;
}
int check_won(void) {
        for (int pile = 0; pile < NUM_DECKS*NUM_SUITS; pile++)
                if (f.f[pile][NUM_RANKS-1] == NO_CARD) return 0;

        return 1;
}
int rank_next (card_t a, card_t b) {
        return get_rank(a) == get_rank(b)-1;
}
int color_ok (card_t a, card_t b) {
#if defined KLONDIKE || defined FREECELL
        /* color opposite? */
        return (get_color(a) != get_color(b));
#elif defined SPIDER
        /* same suit? */
        return (get_suit(a) == get_suit(b));
#endif
}
int is_consecutive (card_t* pile, int pos) {
        if (pos+1 >= PILE_SIZE) return 1; /* card is last */
        if (pile[pos+1] == NO_CARD) return 1; /* card is first */

        /* ranks consecutive? */
        if (!rank_next(pile[pos+1], pile[pos])) return 0;
        /* color/suit OK? */
        if (!color_ok(pile[pos+1], pile[pos])) return 0;

        return 1;
}

int is_movable(card_t* pile, int n) {
#ifdef KLONDIKE
        return(pile[n] > NO_CARD); /*non-movable cards don't exist in klondike*/
#elif defined SPIDER || defined FREECELL
        int top = find_top(pile);
        for (int i = top; i >= 0; i--) {
                if (pile[i] <= NO_CARD) return 0; /*no card or card face down?*/
                if (!is_consecutive(pile, i)) return 0;
                if (i == n) return 1; /* card reached, must be movable */
        }
        return 0;
#endif
}

int hls(card_t card, char* hi) {
        /* checks if a card matches a highlight search. a hilight search might be a rank, a suit, a color or both. */
        // TODO: now we use rankletters in keyboard input and here. that's ugly.
        int ok = 0; /* prevent an invalid highlight from matching everything */
        for (; *hi; hi++) {
                switch(*hi) {
                /* letter ranks: */
                case 'a': case 'A': if (get_rank(card)!=RANK_A) return 0; ok++; break;
                case '0':
                case 'x': case 'X': if (get_rank(card)!=RANK_X) return 0; ok++; break;
                case 'j': case 'J': if (get_rank(card)!=RANK_J) return 0; ok++; break;
                case 'q': case 'Q': if (get_rank(card)!=RANK_Q) return 0; ok++; break;
                case 'k': case 'K': if (get_rank(card)!=RANK_K) return 0; ok++; break;

                /* suits: */
                case 'c': case 'C': if (get_suit(card)!=CLUBS)  return 0; ok++; break;
                case 'd': case 'D': if (get_suit(card)!=DIAMONDS)return 0;ok++; break;
                case 'h': case 'H': if (get_suit(card)!=HEARTS) return 0; ok++; break;
                case 's': case 'S': if (get_suit(card)!=SPADES) return 0; ok++; break;

                /* colours: */
                case 'r': case 'R': if (get_color(card)!=RED) return 0; ok++; break;
                case 'b': case 'B': if (get_color(card)!=BLK) return 0; ok++; break;

                /* special: */
#if defined KLONDIKE || defined FREECELL
                case 'f': case 'F': { /* highlight cards that go on the foundation next */
                        card_t* foundation = f.f[get_suit(card)];
                        int top = find_top(foundation);
                        if (foundation[top]) {
                                if (rank_next(foundation[top], card) &&
                                    get_suit(card) == get_suit(foundation[top]))
                                        return 1;
                        } else {
                                if (get_rank(card) == RANK_A) return 1;
                        }
                        return 0;}
#endif // NOTE: makes no sense in SPIDER

                /* number ranks: */
                default:
                        if (*hi < '1' || *hi > '9') continue;
                        if (get_rank(card) != *hi - '1') return 0;
                        ok++;
                }
        }

        return ok;
}
//}}}

// takeable actions {{{
#ifdef KLONDIKE
card_t stack_take(void) { /*NOTE: assert(f.w >= 0) */
        card_t card = f.s[f.w];
        /* move stack one over, so there are no gaps in it: */
        for (int i = f.w; i < f.z-1; i++)
                f.s[i] = f.s[i+1];
        f.z--;
        f.w--; /* make previous card visible again */
        return card;
}
int t2f(int from, int to, int opt) { /* tableu to foundation */
        (void) to; (void) opt; /* don't need */
        int top_from = find_top(f.t[from]);
        to = get_suit(f.t[from][top_from]);
        int top_to   = find_top(f.f[to]);
        if ((top_to < 0 && get_rank(f.t[from][top_from]) == RANK_A)
        || (top_to >= 0 && rank_next(f.f[to][top_to],f.t[from][top_from]))) {
                f.f[to][top_to+1] = f.t[from][top_from];
                f.t[from][top_from] = NO_CARD;
                undo_push(from, FOUNDATION, to,
                turn_over(f.t[from]));
                if (check_won()) return WON;
                return OK;
        } else return ERR;
}
int w2f(int from, int to, int opt) { /* waste to foundation */
        (void) from; (void) to; (void) opt; /* don't need */
        if (f.w < 0) return ERR;
        to = get_suit(f.s[f.w]);
        int top_to = find_top(f.f[to]);
        if ((top_to < 0 && get_rank(f.s[f.w]) == RANK_A)
        || (top_to >= 0 && rank_next(f.f[to][top_to], f.s[f.w]))) {
                undo_push(WASTE, FOUNDATION, f.w | to<<16, 0);//ugly encoding :|
                f.f[to][top_to+1] = stack_take();
                if (check_won()) return WON;
                return OK;
        } else return ERR;
        
}
int s2w(int from, int to, int opt) { /* stock to waste */
        (void) from; (void) to; (void) opt; /* don't need */
        if (f.z == 0) return ERR;
        f.w++;
        if (f.w == f.z) f.w = -1;
        return OK;
}
int w2s(int from, int to, int opt) { /* waste to stock (undo stock to waste) */
        (void) from; (void) to; (void) opt; /* don't need */
        if (f.z == 0) return ERR;
        f.w--;
        if (f.w < -1) f.w = f.z-1;
        return OK;
}
int f2t(int from, int to, int opt) { /* foundation to tableu */
        (void) from; /* don't need */
        int top_to = find_top(f.t[to]);
        from = opt;
        int top_from = find_top(f.f[from]);
        
        if (color_ok(f.t[to][top_to], f.f[from][top_from])
        && (rank_next(f.f[from][top_from], f.t[to][top_to]))) {
                f.t[to][top_to+1] = f.f[from][top_from];
                f.f[from][top_from] = NO_CARD;
                undo_push(FOUNDATION, to, from, 0);
                return OK;
        } else return ERR;
}
int w2t(int from, int to, int opt) { /* waste to tableu */
        (void) from; (void) opt; /* don't need */
        if (f.w < 0) return ERR;
        int top_to = find_top(f.t[to]);
        if ((color_ok(f.t[to][top_to], f.s[f.w])
           && (rank_next(f.s[f.w], f.t[to][top_to])))
        || (top_to < 0 && get_rank(f.s[f.w]) == RANK_K)) {
                undo_push(WASTE, to, f.w, 0);
                f.t[to][top_to+1] = stack_take();
                return OK;
        } else return ERR;
}
int t2t(int from, int to, int opt) { /* tableu to tableu */
        (void) opt; /* don't need */
        int top_to = find_top(f.t[to]);
        int top_from = find_top(f.t[from]);
        for (int i = top_from; i >=0; i--) {
                if ((color_ok(f.t[to][top_to], f.t[from][i])
                   && (rank_next(f.t[from][i], f.t[to][top_to]))
                   && f.t[from][i] > NO_CARD) /* card face up? */
                || (top_to < 0 && get_rank(f.t[from][i]) == RANK_K)) {
                        /* move cards [i..top_from] to their destination */
                        int count = 0;
                        for (;i <= top_from; i++) {
                                top_to++;
                                f.t[to][top_to] = f.t[from][i];
                                f.t[from][i] = NO_CARD;
                                count++;
                        }
                        undo_push(from, to, count,
                        turn_over(f.t[from]));
                        return OK;
                }
        }
        return ERR; /* no such move possible */
}
#elif defined SPIDER
int remove_if_complete (int pileno) { //cleanup!
        card_t* pile = f.t[pileno];
        /* test if K...A complete; move to foundation if so */
        int top_from = find_top(pile);
        if (get_rank(pile[top_from]) != RANK_A) return 0;
        for (int i = top_from; i>=0; i--) {
                if (!is_consecutive (pile, i)) return 0;
                if (i+RANK_K == top_from /* if ace to king: remove it */
                    && get_rank(pile[top_from-RANK_K]) == RANK_K) {
                        for(int i=top_from, j=0; i>top_from-NUM_RANKS; i--,j++){
                                f.f[f.w][j] = pile[i];
                                pile[i] = NO_CARD;
                        }
                        undo_push(pileno, FOUNDATION, f.w,
                        turn_over(pile));
                        f.w++;
                        return 1;
                }
        }

        return 0;
}
int t2t(int from, int to, int opt) { //in dire need of cleanup
        int top_from = find_top(f.t[from]);
        int top_to = find_top(f.t[to]);
        int empty_to = (top_to < 0)? opt: -1; /* empty pile? */

        for (int i = top_from; i >= 0; i--) {
                if (!is_consecutive(f.t[from], i)) break;

                /* is consecutive OR to empty pile and rank ok? */
                if (rank_next(f.t[from][i], f.t[to][top_to])
                || (empty_to >= RANK_A && get_rank(f.t[from][i]) == empty_to)) {
                        int count = 0;
                        for (;i <= top_from; i++) {
                                top_to++;
                                f.t[to][top_to] = f.t[from][i];
                                f.t[from][i] = NO_CARD;
                                count++;
                        }
                        undo_push(from, to, count,
                        turn_over(f.t[from]));
                        remove_if_complete(to);
                        if (check_won()) return WON;
                        return OK;
                }
        }

        return ERR; /* no such move possible */
}
int s2t(int from, int to, int opt) {
        (void) from; (void) to; (void) opt; /* don't need */
        if (f.z <= 0) return ERR; /* stack out of cards */
        for (int pile = 0; pile < NUM_PILES; pile++)
                if (f.t[pile][0]==NO_CARD) return ERR; /*no piles may be empty*/

        undo_push(STOCK, TABLEU, 1, 0); /* NOTE: before remove_if_complete()! */
        for (int pile = 0; pile < NUM_PILES; pile++) {
                f.t[pile][find_top(f.t[pile])+1] = f.s[--f.z];
                remove_if_complete(pile);
                if (check_won()) return WON;
        }
        return OK;
}
int t2f(int from, int to, int opt) {
        (void) to; (void) opt; /* don't need */
        /* manually retrigger remove_if_complete() (e.g. after undo_pop) */
        return remove_if_complete(from)?OK:ERR;
}
#elif defined FREECELL
int max_move(int from, int to) {
        /* returns the maximum number of cards that can be moved */
        /* see also: https://boardgames.stackexchange.com/a/45157/26498 */
        int free_tabs = 0, free_cells = 0;
        for (int i = 0; i < NUM_PILES; i++) free_tabs  += f.t[i][0] == NO_CARD;
        for (int i = 0; i < NUM_CELLS; i++) free_cells += f.s[i]    == NO_CARD;

        /* don't count the tableau we are moving to: */
        if (to >= 0 && f.t[to][0] == NO_CARD) free_tabs--;

        /* theoretic maximum is limited by the number of cards on the pile */
        int max_theory = (1<<free_tabs) * (free_cells + 1);
        int max_effective = 1 + find_top(f.t[from]) - first_movable(f.t[from]);
        return max_effective < max_theory? max_effective : max_theory;
}
//TODO FREECELL: auto move to tableu after each move (not all cards possible, only when it is the smallest rank still on the board)
int t2t(int from, int to, int opt) {
        int top_to = find_top(f.t[to]);
        int top_from = find_top(f.t[from]);
        int cards = max_move(from, to);
        if (top_to < 0) { /* moving to empty pile? */
                if (opt > cards)
                        return ERR; /* cannot execute move */
                cards = opt; /* user wants to move n cards*/
        }

        for (int i = top_from; i >=0; i--) {
                if (cards-->0/*enough space and not more attempted than wanted*/
                && ((top_to >= 0 /* if destn. not empty: check rank/color */
                   && (color_ok(f.t[to][top_to], f.t[from][i])
                   && (rank_next(f.t[from][i], f.t[to][top_to]))))
                || (top_to < 0 && !cards))) {/*if dest empty and right # cards*/
                        /* move cards [i..top_from] to their destination */
                        int count = 0;
                        for (;i <= top_from; i++) {
                                top_to++;
                                f.t[to][top_to] = f.t[from][i];
                                f.t[from][i] = NO_CARD;
                                count++;
                        }
                        undo_push(from, to, count, 0);
                        return OK;
                }
        }
        return ERR; /* no such move possible */
}
int t2f(int from, int to, int opt) { /* 1:1 copy from KLONDIKE */
        (void) to; (void) opt; /* don't need */
        int top_from = find_top(f.t[from]);
        to = get_suit(f.t[from][top_from]);
        int top_to   = find_top(f.f[to]);
        if ((top_to < 0 && get_rank(f.t[from][top_from]) == RANK_A)
        || (top_to >= 0 && rank_next(f.f[to][top_to],f.t[from][top_from]))) {
                f.f[to][top_to+1] = f.t[from][top_from];
                f.t[from][top_from] = NO_CARD;
                undo_push(from, FOUNDATION, to, 0);
                if (check_won()) return WON;
                return OK;
        } else return ERR;
}
int f2t(int from, int to, int opt) {
        (void) from; /* don't need */
        int top_to = find_top(f.t[to]);
        from = opt;
        int top_from = find_top(f.f[from]);

        if (top_to < 0 /* empty tableu? */
        ||(color_ok(f.t[to][top_to], f.f[from][top_from])
        && (rank_next(f.f[from][top_from], f.t[to][top_to])))) {
                f.t[to][top_to+1] = f.f[from][top_from];
                f.f[from][top_from] = NO_CARD;
                undo_push(FOUNDATION, to, from, 0);
                return OK;
        } else return ERR;
}
int t2c(int from, int to, int opt) {
        (void) to; (void) opt; /* don't need */
        /* is a cell free? */
        if (f.w == (1<<NUM_CELLS)-1)
                return ERR;
        for (to = 0; to < NUM_CELLS; to++)
                if (!(f.w>>to&1)) break;
        /* move 1 card */
        int top_from = find_top(f.t[from]);
        f.s[to] = f.t[from][top_from];
        f.t[from][top_from] = NO_CARD;
        f.w |= 1<<to; /* mark cell as occupied */
        undo_push(from, STOCK, to, 0);

        return OK;
}
int c2t(int from, int to, int opt) {
        (void) from; /* don't need */
        int top_to = find_top(f.t[to]);
        from = opt;

        if (top_to < 0 /* empty tableu? */
        ||(color_ok(f.t[to][top_to], f.s[from])
        && (rank_next(f.s[from], f.t[to][top_to])))) {
                f.t[to][top_to+1] = f.s[from];
                f.s[from] = NO_CARD;
                f.w &= ~(1<<from); /* mark cell as free */
                undo_push(STOCK, to, from, 0);
                return OK;
        } else return ERR;
        return ERR;
}
int c2f(int from, int to, int opt) {
        (void) from; (void) to; /* don't need */
        from = opt;
        if (f.s[from] == NO_CARD) return ERR;
        to = get_suit(f.s[from]);
        int top_to = find_top(f.f[to]);
        if ((top_to < 0 && get_rank(f.s[from]) == RANK_A)
        || (top_to >= 0 && rank_next(f.f[to][top_to],f.s[from]))) {
                f.f[to][top_to+1] = f.s[from];
                f.s[from] = NO_CARD;
                f.w &= ~(1<<from); /* mark cell as free */
                undo_push(STOCK, FOUNDATION, from | to<<16, 0);
                if (check_won()) return WON;
                return OK;
        } else return ERR;
}
int f2c(int from, int to, int opt) {
        (void) from; (void) to; /* don't need */
        /* is a cell free? */
        if (f.w == (1<<NUM_CELLS)-1)
                return ERR;
        for (to = 0; to < NUM_CELLS; to++)
                if (!(f.w>>to&1)) break;
        /* move 1 card */
        from = opt;
        int top_from = find_top(f.f[from]);
        f.s[to] = f.f[from][top_from];
        f.f[from][top_from] = NO_CARD;
        f.w |= 1<<to; /* mark cell as occupied */
        undo_push(FOUNDATION, STOCK, from | to<<16, 0);

        return OK;
}
#define w2f c2f /* for join()'s "to foundation" */
#endif

//TODO: generalize prediction engine for CMD_HINT
#ifdef KLONDIKE
#define would_complete(pile) 0
#elif defined SPIDER
#define would_complete(pile) \
        (get_rank(f.t[pile][r[pile].top]) == RANK_A \
        && get_rank(f.t[to][bottom_to]) == RANK_K)
#elif defined FREECELL
#define would_complete(pile) 0
#endif
#define would_turn(pile) \
        (f.t[pile][r[pile].pos-1] < 0)
#define would_empty(pile) \
        (r[pile].pos == 0)

int join(int to) {
        int top_to = find_top(f.t[to]);
#ifdef SPIDER
        int bottom_to = first_movable(f.t[to]);
#endif

#if defined KLONDIKE || defined FREECELL
        if (to == WASTE || to == STOCK) return ERR; /*why would you do that!?*/

        if (to == FOUNDATION) {
                int status = ERR;
                for (int i = 0; i < NUM_PILES+NUM_CELLS; i++)
                        switch (is_tableu(i)?t2f(i, FOUNDATION, 0)
                                            :w2f(STOCK,FOUNDATION,i-NUM_PILES)){
                        case WON: return WON;
                        case OK:  status = OK;
                        case ERR: /* nop */;
                        }
                return status;
        }
#endif

#ifdef KLONDIKE
        if (top_to < 0) { /* move a king to empty pile: */
                for (int i = 0; i <= TAB_MAX; i++) {
                        if (f.t[i][0] < 0) /* i.e. would turn? */
                                if (t2t(i, to, 0) == OK) return OK;
                }
                return w2t(WASTE, to, 0);
        }
#elif defined FREECELL
        if (top_to < 0) { /* move longest cascade to empty tableu: */ //TODO FREECELL:
                int longest = -1;
                int length = -1;
                for (int i = 0; i <= TAB_MAX; i++) {
                        int m = max_move(i, to);
                        /*longest cascade that won't uncover another free pile*/
                        //TODO: don't rip apart cascades
                        if (m >= length && m <= find_top(f.t[i]))
                                length = m, longest = i;
                }
                if (longest < 0) return ERR;
                return t2t(longest, to, length);
        }
#endif

        struct rating {
                int ok:1;    /* card to move in pile? */
                int above;   /* number of movable cards above */
                int below;   /* number of cards below ours */
                int pos;     /* where the card to move is in the pile */
                int top;     /* find_top() */
        } r[NUM_PILES] = {{0}};
        int complete = 0;/* SPIDER: true if any pile would complete a stack */
        int turn =  0; /* SPIDER: true if any pile would turn_over */
        int empty = 0; /* true if any pile would become empty */

        /* 1. rate each pile: */
#ifdef SPIDER
        if (top_to < 0) {
                for (int pile = 0; pile < NUM_PILES; pile++) {
                        if (pile == to) continue;
                        int top = find_top(f.t[pile]);
                        int bottom = first_movable(f.t[pile]);
                        r[pile].pos = bottom; /* need for would_empty */

                        if (top < 0) continue; /* no cards to move */
                        if (would_empty(pile)) continue; /* doesn't help */

                        r[pile].ok++;
                        r[pile].above = 0; /* always take as many as possible */
                        r[pile].below = top - bottom;
                        r[pile].top = top;
                        complete |= would_complete(pile); /* never happens */
                        turn     |= would_turn(pile);
                        empty    |= would_empty(pile);
                }
        } else
#endif
        for (int pile = 0; pile < NUM_PILES; pile++) {
                r[pile].top = r[pile].pos = find_top(f.t[pile]);
                /* backtrack until we find a compatible-to-'to'-pile card: */
#ifdef FREECELL
                int maxmove = max_move(pile, -1);
#endif
                while (r[pile].pos >= 0 && is_movable(f.t[pile], r[pile].pos)) {
                        int rankdiff = get_rank(f.t[pile][r[pile].pos])
                                       - get_rank(f.t[to][top_to]);
                        if (rankdiff >= 0) break; /* past our card */
#ifdef FREECELL
                        if (!maxmove--) break; /* can't move this many cards */
#endif
                        if (rankdiff == -1 && /* rank matches */
                           color_ok(f.t[pile][r[pile].pos], f.t[to][top_to])
                        ) {
                                r[pile].ok++;
                                complete |= would_complete(pile);
                                turn     |= would_turn(pile);
                                empty    |= would_empty(pile);
                                for (int i = r[pile].pos; i >= 0; i--)
                                        if (is_movable(f.t[pile], i-1))
                                                r[pile].above++;
                                        else break;
                                break;
                        }
                        r[pile].pos--;
                        r[pile].below++;
                }
        }

        /* 2. find optimal pile: (optimized for spider) */
        //todo: in spider, prefer longest piles if above==0 (faster completions)
        int from = -1;
        for (int pile = 0, above = 99, below = 99; pile < NUM_PILES; pile++) {
                if (!r[pile].ok) continue;
                /* don't bother if another pile would be better: prefer ... */
                /* ... to complete a stack: */
                if (!would_complete(pile) && complete) continue;
                /* ... emptying piles: */
                if (!would_empty(pile) && empty && !complete) continue;
                /* ... to turn_over: */
                if (!would_turn(pile) && turn && !complete && !empty) continue;
                /* ... not to rip apart too many cards: */
                if (r[pile].above > above) continue;
                /* if tied, prefer ... */
                if (r[pile].above == above
                   /* ... larger pile if destination is empty */
                   && (top_to < 0? r[pile].below < below
                   /* ... shorter pile otherwise */
                                 : r[pile].below > below))
                        continue;

                from = pile;
                above = r[pile].above;
                below = r[pile].below;
        }

        /* 3. move cards over and return: */
#ifdef KLONDIKE
        /* prefer waste if it wouldn't turn_over: */
        /* NOTE: does not attempt to take from froundation */
        if (!empty && !turn && w2t(WASTE, to, 0) == OK)
                return OK;
        if (from < 0) /* nothing found */
                return ERR;
        return t2t(from, to, 0);
#elif defined SPIDER
        if (from < 0) /* nothing found */
                return ERR;
        int bottom = first_movable(f.t[from]);
        return t2t(from, to, get_rank(f.t[from][bottom]));
#elif defined FREECELL
        //TODO: if would rip apart, try freecells first (instead after)
        if (from < 0) /* no tableu move found */ {
                /* try all free cells before giving up: */
                for (int i = 0; i < NUM_CELLS; i++)
                        if (c2t(STOCK, to, i) == OK) return OK;
                return ERR;
        }
        return t2t(from, to, 0);
#endif
}
#undef would_empty
#undef would_turn
#undef would_complete
int nop(int from, int to, int opt) { (void)from;(void)to;(void)opt;return ERR; }
// }}}

// keyboard input handling {{{
// cursor functions{{{
#ifdef KLONDIKE
void cursor_left (struct cursor* cursor) {
        op.h = 1;
        if (is_tableu(cursor->pile)) {
                if (cursor->pile > 0) cursor->pile--;
                cursor->opt = 0;
        } else { /* stock/waste/foundation*/
                switch (cursor->pile) {
                case WASTE: cursor->pile = STOCK; cursor->opt = 0; break;
                case FOUNDATION:
                        if (cursor->opt <= 0)
                                cursor->pile = WASTE;
                        else
                                cursor->opt--;
                }
        }
}
void cursor_down (struct cursor* cursor) {
        op.h = 1;
        if (!is_tableu(cursor->pile)) {
                switch (cursor->pile) {
                case STOCK: cursor->pile = TAB_1; break;
                case WASTE: cursor->pile = TAB_2; break;
                case FOUNDATION:
                        cursor->pile = TAB_4 + cursor->opt;
                }
                cursor->opt = 0;
        }
}
void cursor_up (struct cursor* cursor) {
        op.h = 1;
        if (is_tableu(cursor->pile)) {
                switch (cursor->pile) { //ugly :|
                case TAB_1: cursor->pile = STOCK; break;
                case TAB_2: cursor->pile = WASTE; break;
                case TAB_3: cursor->pile = WASTE; break;
                case TAB_4: case TAB_5: case TAB_6: case TAB_7:
                        cursor->opt=cursor->pile-TAB_4;
                        cursor->pile = FOUNDATION;
                        break;
                }
        }
}
void cursor_right (struct cursor* cursor) {
        op.h = 1;
        if (is_tableu(cursor->pile)) {
                if (cursor->pile < TAB_MAX) cursor->pile++;
                cursor->opt = 0;
        } else {
                switch (cursor->pile) {
                case STOCK: cursor->pile = WASTE; break;
                case WASTE: cursor->pile = FOUNDATION;cursor->opt = 0; break;
                case FOUNDATION:
                        if (cursor->opt < NUM_SUITS-1)
                                cursor->opt++;
                }
        }
}
#elif defined SPIDER
/*NOTE: one can't highlight the stock due to me being too lazy to implement it*/
void cursor_left (struct cursor* cursor) {
        op.h = 1;
        if (cursor->pile > 0) cursor->pile--;
        cursor->opt = 0;
}
void cursor_down (struct cursor* cursor) {
        op.h = 1;
        int first = first_movable(f.t[cursor->pile]);
        int top = find_top(f.t[cursor->pile]);
        if (first + cursor->opt < top)
                cursor->opt++;
}
void cursor_up (struct cursor* cursor) {
        op.h = 1;
        if (cursor->opt > 0) cursor->opt--;
}
void cursor_right (struct cursor* cursor) {
        op.h = 1;
        if (cursor->pile < TAB_MAX) cursor->pile++;
        cursor->opt = 0;
}
#elif defined FREECELL
void cursor_left (struct cursor* cursor) {
        op.h = 1;
        if (is_tableu(cursor->pile)) {
                if (cursor->pile > 0) cursor->pile--;
                cursor->opt = 0;
        } else { /* cells/foundation*/
                switch (cursor->pile) {
                case STOCK:
                        if (cursor->opt > 0)
                                cursor->opt--;
                        break;
                case FOUNDATION:
                        if (cursor->opt <= 0) {
                                cursor->pile = STOCK;
                                cursor->opt = 3;
                        } else {
                                cursor->opt--;
                        }
                }
        }
}
void cursor_down (struct cursor* cursor) {
        op.h = 1;
        if (is_tableu(cursor->pile)) {
                if (cursor->opt < max_move(cursor->pile, -1)-1)
                        cursor->opt++;
        } else {
                cursor->pile = cursor->opt+NUM_CELLS*(cursor->pile==FOUNDATION);
                cursor->opt = 0;
        }
}
void cursor_up (struct cursor* cursor) {
        op.h = 1;
        if (is_tableu(cursor->pile)) {
                if (cursor->opt > 0) {
                        cursor->opt--;
                } else {
                        switch (cursor->pile) {
                        case TAB_1: case TAB_2: case TAB_3: case TAB_4:
                                cursor->opt = cursor->pile; /*assumes TAB_1==0*/
                                cursor->pile = STOCK;
                                break;
                        case TAB_5: case TAB_6: case TAB_7: case TAB_8:
                                cursor->opt = cursor->pile - NUM_CELLS;
                                cursor->pile = FOUNDATION;
                        }
                }
        }
}
void cursor_right (struct cursor* cursor) {
        op.h = 1;
        if (is_tableu(cursor->pile)) {
                if (cursor->pile < TAB_MAX) cursor->pile++;
                cursor->opt = 0;
        } else {
                switch (cursor->pile) {
                case STOCK:
                        if (cursor->opt < NUM_SUITS-1) {
                                cursor->opt++;
                        } else {
                                cursor->pile = FOUNDATION;
                                cursor->opt = 0;
                        } break;
                case FOUNDATION:
                        if (cursor->opt < NUM_SUITS-1)
                                cursor->opt++;
                }
        }
}
#endif
void cursor_to (struct cursor* cursor, int pile) {
        op.h = 1;
        cursor->pile = pile;
        cursor->opt = 0;
}
int set_mouse(int pile, int* main, int* opt) {
//TODO: this should set cursor.opt, so card selector choice dialog does not trigger!
        op.h = 0;
        if (pile < 0) return 1;
        *main = pile;
#ifdef KLONDIKE
        if (pile >= FOUNDATION)//TODO: check upper bound!
                *main = FOUNDATION,
                *opt  = pile - FOUNDATION;
#elif defined SPIDER
        (void)opt;
#elif defined FREECELL
        if (pile > TAB_MAX) {
                *main = pile-STOCK < NUM_CELLS? STOCK : FOUNDATION;
                *opt = (pile-STOCK) % 4;
        }
#endif
        return 0;
}
//}}}
int get_cmd (int* from, int* to, int* opt) {
        int _f, t;
        unsigned char mouse[6] = {0}; /* must clear [3]! */
        struct cursor inactive = {-1,-1};
        static struct cursor active = {0,0};
        static char last_successful_action[2] = {0,0}; //TODO: dot implementation should be in main game loop (CMD_AGAIN)
        if (is_tableu(active.pile))
                active.opt = 0;

        /***/
from_l: print_table(&active, &inactive);
        _f = getch(mouse);

        switch (_f) {
        /* direct addressing: */
        case '1': *from = TAB_1; break;
        case '2': *from = TAB_2; break;
        case '3': *from = TAB_3; break;
        case '4': *from = TAB_4; break;
        case '5': *from = TAB_5; break;
        case '6': *from = TAB_6; break;
        case '7': *from = TAB_7; break;
#ifdef SPIDER
        case '8': *from = TAB_8; break;
        case '9': *from = TAB_9; break;
        case '0': *from = TAB_10;break;
#elif defined FREECELL
        case '8': *from = TAB_8; break;
        case '9': *from = STOCK; break;
        case '0': *from = FOUNDATION; break;
#elif defined KLONDIKE
        case '9': *from = WASTE; break;
        case '0': *from = FOUNDATION; break;
        case '8': /* fallthrough */
#endif
#ifndef FREECELL
        case '\n': *from = STOCK; break;
#endif
        /* cursor keys addressing: */
        case KEY_LEFT:
        case 'h': cursor_left (&active); goto from_l;
        case KEY_DOWN:
        case 'j': cursor_down (&active); goto from_l;
        case KEY_UP:
        case 'k': cursor_up   (&active); goto from_l;
        case KEY_RIGHT:
        case 'l': cursor_right(&active); goto from_l;
        case KEY_HOME:
        case 'H': cursor_to(&active,TAB_1);  goto from_l; /* leftmost  tableu */
        case KEY_END:
        case 'L': cursor_to(&active,TAB_MAX);goto from_l; /* rigthmost tableu */
        case KEY_INS:
        case 'M': cursor_to(&active,TAB_MAX/2); goto from_l; /* center tableu */
        case ' ': /* continue with second cursor */
                *from = active.pile;
#ifdef KLONDIKE
                *opt = active.opt; /* when FOUNDATION */
#endif
                inactive = active;
                break;
        /* mouse addressing: */
        case MOUSE_MIDDLE: return CMD_NONE;
        case MOUSE_RIGHT:
                if (set_mouse(term2pile(mouse), to, opt))
                        return CMD_INVAL;
                return CMD_JOIN;
        case MOUSE_LEFT:
                if (set_mouse(term2pile(mouse), from, opt))
                        return CMD_INVAL;
                if (!is_tableu(*from))
                        inactive.opt = *opt; /* prevents card selector dialog */
                break;
        /* misc keys: */
        case '.':
                ungetc(last_successful_action[1], stdin);
                ungetc(last_successful_action[0], stdin); //XXX: 2nd ungetc() not portable!
                goto from_l;
        case ':':
                {char buf[256];
                fprintf (stderr, ":");
                raw_mode(0); /* turn on echo */
                fgets (buf, 256, stdin);
                raw_mode(1);
                switch(buf[0]) {
                case 'q': return CMD_QUIT;
                case 'n': return CMD_NEW;
                case 'r': return CMD_AGAIN;
                case 'h': return CMD_HELP;
                default:  return CMD_INVAL;
                }}
        case 'J':
                *to = active.pile;
                return CMD_JOIN;
        case 'K': /* fallthrough */
        case '?': return CMD_HINT;
        case 'f': return CMD_FIND;
        case '/': return CMD_SEARCH;
        case 'u': return CMD_UNDO;
        case 002: return CMD_NONE; /* sent by SIGWINCH */
        case EOF: return CMD_NONE; /* sent by SIGCONT */
        default: return CMD_INVAL;
        }
        inactive.pile = *from; /* for direct addressing highlighting */

        /* prevent taking from empty tableu pile: */
        if (is_tableu(*from) && f.t[*from][0] == NO_CARD) return CMD_INVAL;

        /* prevent taking from empty stock: */
#ifdef KLONDIKE
        if (*from == WASTE && f.w == -1) return CMD_INVAL;
#elif defined FREECELL
        /* basic test and direct addressing: */
        if (*from == STOCK && !(f.s[0]||f.s[1]||f.s[2]||f.s[3]))
                return CMD_INVAL;
        /* cursor keys addressing: */
        if (active.pile == STOCK && f.s[active.opt] == NO_CARD)
                return CMD_INVAL;
        /* mouse addressing: */
        if (inactive.pile == STOCK && inactive.opt > -1 && f.s[inactive.opt] == NO_CARD)
                return CMD_INVAL;
#endif

        /* prevent taking from empty foundation pile: */
#ifndef SPIDER
        /* basic test and direct addressing: */
        if (*from == FOUNDATION && !(*f.f[0]||*f.f[1]||*f.f[2]||*f.f[3]))
                return CMD_INVAL;
        /* cursor keys addressing: */
        if (active.pile == FOUNDATION && f.f[active.opt] == NO_CARD)
                return CMD_INVAL;
        /* mouse addressing: */
        if (inactive.pile == FOUNDATION && inactive.opt > -1 && *f.f[inactive.opt] == NO_CARD)
                return CMD_INVAL;
#endif

#ifndef FREECELL
        if (*from == STOCK) {
                *to = WASTE;
                return CMD_MOVE;
        }
#endif

        /***/
to_l:   print_table(&active, &inactive);
        t = getch(mouse);

        switch (t) {
        case KEY_LEFT:
        case 'h': cursor_left (&active); goto to_l;
        case KEY_DOWN:
        case 'j': cursor_down (&active); goto to_l;
        case KEY_UP:
        case 'k': cursor_up   (&active); goto to_l;
        case KEY_RIGHT:
        case 'l': cursor_right(&active); goto to_l; 
        case KEY_HOME:
        case 'H': cursor_to(&active,TAB_1);     goto to_l;
        case KEY_END:
        case 'L': cursor_to(&active,TAB_MAX);   goto to_l;
        case KEY_INS:
        case 'M': cursor_to(&active,TAB_MAX/2); goto to_l;
        case 'J': /* fallthrough; just join selected pile */
        case ' ':
                *to = active.pile;
                break; /* continues with the foundation/empty tableu check */
        case MOUSE_MIDDLE:
        case MOUSE_RIGHT: return CMD_NONE;
        case MOUSE_LEFT:
                if (set_mouse(term2pile(mouse), to, opt))
                        return CMD_INVAL;
                break;
        case 'K': /* fallthrough */
        case '?': return CMD_HINT;
        case 'f': return CMD_FIND; // XXX: will cancel from-card
        case '/': return CMD_SEARCH; //ditto.
        case 'u': return CMD_NONE; /* cancel selection */
        case EOF: return CMD_NONE; /* sent by SIGCONT */
        default:
                if (t < '0' || t > '9') return CMD_INVAL;
                if (t == '0')
#ifdef KLONDIKE
                        *to = FOUNDATION;
#elif defined SPIDER
                        *to = TAB_10;
#elif defined FREECELL
                        *to = FOUNDATION;
                else if (t == '9')
                        *to = STOCK;
#endif
                else
                        *to = t-'1';
        }
        last_successful_action[0] = _f;
        last_successful_action[1] = t;

        /***/
        /* direct addressing post-processing stage:
        because foundations/freecells share the same key (and you can't select
        partial piles) there are sometimes ambiguous situations where it isn't
        clear from which pile (or how many cards) to take. the code below will
        only ask the user if there are at least two possible moves and
        automatically choose otherwise. */
#ifdef FREECELL
        /* if it was selected with a cursor, it's obvious: */
        if (inactive.opt >= 0) {
                if (is_tableu(*from)) {
                        /* NOTE: max_move same as in cursor_down() */
                        *opt = max_move(*from, -1) - inactive.opt;
                } else {
                        *opt = inactive.opt;
                }
        /* moving from tableu to empty tableu? */
        } else if(is_tableu(*from) && is_tableu(*to) && f.t[*to][0] == NO_CARD){
                int top = find_top(f.t[*from]);
                int max = max_move(*from, *to);
                int rank;
                if (top < 0) return CMD_INVAL;
                if (max == 1) { /* only 1 movable? */
                        return *opt = 1, CMD_MOVE;
                } else { /* only ask the user if it's unclear: */
                        int bottom = top - (max-1);
                        printf ("\rup to ([a23456789xjqk] or space/return): ");
                        rank = getch(NULL);
                        switch (rank) {
                        case ' ': rank = get_rank(f.t[*from][top]); break;
                        case'\n': rank = get_rank(f.t[*from][bottom]); break;
                        case 'a': case 'A': rank = RANK_A; break;
                        case '0': /* fallthrough */
                        case 'x': case 'X': rank = RANK_X; break;
                        case 'j': case 'J': rank = RANK_J; break;
                        case 'q': case 'Q': rank = RANK_Q; break;
                        case 'k': case 'K': rank = RANK_K; break;
                        default: rank -= '1';
                        }
                        if (rank < RANK_A || rank > RANK_K) return CMD_INVAL;

                        for (int i = 0; max--; i++)
                                if (get_rank(f.t[*from][top-i]) == rank)
                                        return *opt = 1+i, CMD_MOVE;

                        return CMD_INVAL;
                }
                /* `opt` is the number of cards to move */
        /* moving between stock/foundation? */
        } else if (*from == FOUNDATION && *to == FOUNDATION) {
                return CMD_INVAL; /* nonsensical */
        } else if (*from == FOUNDATION && *to == STOCK) {
                if (f.w == (1<<NUM_CELLS)-1) return CMD_INVAL; /*no free cells*/
                int ok_foundation; /* find compatible (non-empty) foundations:*/
                int used_fs=0; for (int i = 0; i < NUM_SUITS; i++)
                        if (!!f.f[i][0]) ok_foundation = i, used_fs++;

                if (used_fs == 0) return CMD_INVAL; /* nowhere to take from */
                if (used_fs == 1) { /* take from the only one */
                        return *opt = ok_foundation, CMD_MOVE;
                } else { /* ask user */
                        printf ("take from (1-4): "); fflush (stdout);
                        *opt = getch(NULL) - '1';
                        if (*opt < 0 || *opt > 3) return CMD_INVAL;
                }
                /* `opt` is the foundation index (0..3) */
        } else if (*from == STOCK) { /* cell -> foundation/tableu */
                if (!f.w) return CMD_INVAL; /* no cell to take from */
                int ok_cell; /* find compatible (non-empty) cells: */
                int tab = is_tableu(*to);
                int used_cs=0; for (int i = 0; i < NUM_CELLS; i++) {
                        card_t* pile = (tab?f.t[*to]:f.f[get_suit(f.s[i])]);
                        int top_to = find_top(pile);
                        if (tab? /* to tableu? */
                                ((top_to<0 && f.s[i] > NO_CARD)
                                ||(top_to>=0 && rank_next(f.s[i], pile[top_to])
                                             && color_ok(f.s[i], pile[top_to])))
                        : /* to foundation? */
                                ((top_to<0 && get_rank(f.s[i]) == RANK_A)
                                ||(top_to>=0 && rank_next(pile[top_to],f.s[i])))
                        )
                                ok_cell = i, used_cs++;
                }

                if (used_cs == 0) return CMD_INVAL; /* nowhere to take from */
                if (used_cs == 1) { /* take from the only one */
                        return *opt = ok_cell, CMD_MOVE;
                } else { /* ask user */
                        printf ("take from (1-4): "); fflush (stdout);
                        *opt = getch(NULL) - '1';
                        if (*opt < 0 || *opt > 3) return CMD_INVAL;
                }
                /* `opt` is the cell index (0..3) */
        } else
#endif
//TODO: mouse-friendly "up to?" dialog
#if defined KLONDIKE || defined FREECELL
        if (*from == FOUNDATION) {
                if (inactive.opt >= 0) {
                        *opt = inactive.opt;
                        return CMD_MOVE;
                }
                int top = find_top(f.t[*to]);
                if (top < 0) return CMD_INVAL;
                int color = get_color(f.t[*to][top]);
                int choice_1 = 1-color; /* selects piles of   */
                int choice_2 = 2+color; /* the opposite color */
                int top_c1 = find_top(f.f[choice_1]);
                int top_c2 = find_top(f.f[choice_2]);

                switch ((rank_next(f.f[choice_1][top_c1], f.t[*to][top])
                         && top_c1 >= 0 ) << 0
                       |(rank_next(f.f[choice_2][top_c2], f.t[*to][top])
                         && top_c2 >= 0 ) << 1) {
                case (       1<<0): *opt = choice_1; break; /* choice_1 only */
                case (1<<1       ): *opt = choice_2; break; /* choice_2 only */
                case (1<<1 | 1<<0): /* both, ask user which to pick from */
                        printf ("take from (1-4): "); fflush (stdout);
                        *opt = getch(NULL) - '1';
                        if (*opt < 0 || *opt > 3) return CMD_INVAL;
                        break;
                default: return CMD_INVAL; /* none matched */
                }
                /* `opt` is the foundation index (0..3) */
        }
#elif defined SPIDER
        /* moving to empty tableu? */
        if (is_tableu(*to) && f.t[*to][0] == NO_CARD) {
                int bottom = first_movable(f.t[*from]);
                if (inactive.opt >= 0) { /*if from was cursor addressed: */
                        *opt = get_rank(f.t[*from][bottom + inactive.opt]);
                        return CMD_MOVE;
                }
                int top = find_top(f.t[*from]);
                if (top < 0) return CMD_INVAL;
                if (top >= 0 && !is_movable(f.t[*from], top-1)) {
                        *opt = get_rank(f.t[*from][top]);
                } else { /* only ask the user if it's unclear: */
                        printf ("\rup to ([a23456789xjqk] or space/return): ");
                        *opt = getch(NULL);
                        switch (*opt) {
                        case ' ': *opt = get_rank(f.t[*from][top]); break;
                        case'\n': *opt = get_rank(f.t[*from][bottom]); break;
                        case 'a': case 'A': *opt = RANK_A; break;
                        case '0': /* fallthrough */
                        case 'x': case 'X': *opt = RANK_X; break;
                        case 'j': case 'J': *opt = RANK_J; break;
                        case 'q': case 'Q': *opt = RANK_Q; break;
                        case 'k': case 'K': *opt = RANK_K; break;
                        default: *opt -= '1';
                        }
                        if (*opt < RANK_A || *opt > RANK_K) return CMD_INVAL;
                }
                /* `opt` is the rank of the highest card to move */
        }
#endif
        return CMD_MOVE;
}

int getctrlseq(unsigned char* buf) {
        int c;
        enum esc_states {
                START,
                ESC_SENT,
                CSI_SENT,
                MOUSE_EVENT,
        } state = START;
        int offset = 0x20; /* never sends control chars as data */
        while ((c = getchar()) != EOF) {
                switch (state) {
                case START:
                        switch (c) {
                        case '\033': state=ESC_SENT; break;
                        default: return c;
                        }
                        break;
                case ESC_SENT:
                        switch (c) {
                        case '[': state=CSI_SENT; break;
                        default: return KEY_INVAL;
                        }
                        break;
                case CSI_SENT:
                        switch (c) {
                        case 'A': return KEY_UP;
                        case 'B': return KEY_DOWN;
                        case 'C': return KEY_RIGHT;
                        case 'D': return KEY_LEFT;
                        /*NOTE: home/end send ^[[x~ . no support for modifiers*/
                        case 'H': return KEY_HOME;
                        case 'F': return KEY_END;
                        case '2': getchar(); return KEY_INS;
                        case '5': getchar(); return KEY_PGUP;
                        case '6': getchar(); return KEY_PGDN;
                        case 'M': state=MOUSE_EVENT; break;
                        default: return KEY_INVAL;
                        }
                        break;
                case MOUSE_EVENT:
                        if (buf == NULL) return KEY_INVAL;
                        buf[0] = c - offset;
                        buf[1] = getchar() - offset;
                        buf[2] = getchar() - offset;
                        return MOUSE_ANY;
                default:
                        return KEY_INVAL;
                }
        }
        return 2;
}
int term2pile(unsigned char *mouse) {
        int line   = (mouse[2]-1);
        int column = (mouse[1]-1) / op.s->width;

        if (line < op.s->height) { /* first line */
#ifdef KLONDIKE
                switch (column) {
                case 0: return STOCK;
                case 1: return WASTE;
                case 2: return -1; /* spacer */
                case 3: return FOUNDATION+0;
                case 4: return FOUNDATION+1;
                case 5: return FOUNDATION+2;
                case 6: return FOUNDATION+3;
                }
#elif defined SPIDER
                if (column < 3) return STOCK;
                return -1;
#elif defined FREECELL
                if (column < NUM_SUITS + NUM_CELLS) return STOCK+column;
                return -1;
#endif
        } else if (line > op.s->height) { /* tableu */
                if (column <= TAB_MAX) return column;
        }
        return -1;
}
int wait_mouse_up(unsigned char* mouse) {
        //TODO: mouse drag: start gets inactive, hovering gets active cursors
        struct cursor cur = {-1,-1};
        int level = 1;
        /* note: if dragged [3]==1 and second position is in mouse[0,4,5] */

        /* display a cursor while mouse button is pushed: */
        int pile = term2pile(mouse);
        cur.pile = pile;
#ifdef KLONDIKE
        if (pile >= FOUNDATION) {
                cur.pile = FOUNDATION;
                cur.opt = pile-FOUNDATION;
        }
#elif defined FREECELL
        if (pile > TAB_MAX) {
                cur.pile = pile-STOCK < NUM_CELLS? STOCK : FOUNDATION;
                cur.opt = (pile-STOCK) % 4;
        }
#endif
        /* need to temporarily show the cursor, then revert to last state: */
        int old_show_cursor_hi = op.h; //TODO: ARGH! that's awful!
        op.h = 1;
        print_table(&cur, NO_HI); //TODO: should not overwrite inactive cursor!
        op.h = old_show_cursor_hi;

        while (level > 0) {
                if (getctrlseq (mouse+3) == MOUSE_ANY) {
                        /* ignore mouse wheel events: */
                        if (mouse[3] & 0x40) continue;

                        else if((mouse[3]&3) == 3) level--; /* release event */
                        else level++; /* another button pressed */
                }
        }

        int success = mouse[1] == mouse[4] && mouse[2] == mouse[5];
        if (success) {
                mouse[3] = 0;
        }
        return success;
}

int getch(unsigned char* buf) {
//TODO: if buf==NULL disable mouse input
/* returns a character, EOF, or constant for an escape/control sequence - NOT
compatible with the ncurses implementation of same name */
        int action;
        if (buf && buf[3]) {
                /* mouse was dragged; return 'ungetted' previous destination */
                action = MOUSE_DRAG;
                /* keep original [0], as [3] only contains release event */
                buf[1] = buf[4];
                buf[2] = buf[5];
                buf[3] = 0;
        } else {
                action = getctrlseq(buf);
        }

        switch (action) {
        case MOUSE_ANY:
                if (buf[0] > 3) break; /* ignore wheel events */
                wait_mouse_up(buf);
                /* fallthrough */
        case MOUSE_DRAG:
                switch (buf[0]) {
                case 0: return MOUSE_LEFT;
                case 1: return MOUSE_MIDDLE;
                case 2: return MOUSE_RIGHT;
                }
        }

        return action;
}
// }}}

// shuffling and dealing {{{
void deal(long seed) {
//TODO: clear hls/f.h
        f = (const struct playfield){0}; /* clear playfield */
        card_t deck[DECK_SIZE*NUM_DECKS];
        int avail = DECK_SIZE*NUM_DECKS;
        for (int i = 0; i < DECK_SIZE*NUM_DECKS; i++) deck[i] = (i%DECK_SIZE)+1;
#ifdef SPIDER
        if (op.m != NORMAL) for (int i = 0; i < DECK_SIZE*NUM_DECKS; i++) {
                if (op.m == MEDIUM) deck[i] = 1+((deck[i]-1) | 2);
                if (op.m == EASY)   deck[i] = 1+((deck[i]-1) | 2 | 1);
                /* the 1+ -1 dance gets rid of the offset created by NO_CARD */
        }
#endif
        srand (seed);
        for (int i = DECK_SIZE*NUM_DECKS-1; i > 0; i--) { /* fisher-yates */
                int j = rand() % (i+1);
                if (j-i) deck[i]^=deck[j],deck[j]^=deck[i],deck[i]^=deck[j];
        }

        /* deal cards: */
        for (int i = 0; i < NUM_PILES; i++) {
#ifdef KLONDIKE
#define SIGN -
                int count = i; /* pile n has n closed cards, then 1 open */
#elif defined SPIDER
#define SIGN -
                int count = i<4?5:4; /* pile 1-4 have 5, 5-10 have 4 closed */
#elif defined FREECELL
#define SIGN +
                int count = i<4?6:5;/*like spider, but cards are dealt face-up*/
#endif
                /* "SIGN": face down cards are negated */
                for (int j = 0; j < count; j++) f.t[i][j] = SIGN deck[--avail];
                f.t[i][count] = deck[--avail]; /* the face-up card */
#undef SIGN
        }
        /* rest of the cards to the stock: */
        /* NOTE: assert(avail==50) for spider, assert(avail==0) for freecell */
        for (f.z = 0; avail; f.z++) f.s[f.z] = deck[--avail];
#ifdef KLONDIKE
        f.w = -1; /* @start: nothing on waste */
#elif defined SPIDER
        f.w = 0; /* number of used foundations */
#elif defined FREECELL
        f.w = 0; /* bitmask of used free cells */
#endif

        f.u = &undo_sentinel;
}
//}}}

// screen drawing routines {{{
void print_hi(int invert, int grey_bg, int bold, int blink, char* str) {
        if (!op.h) invert = 0; /* don't show invert if we used the mouse last */
        if (bold && op.s == &unicode_large_color){ //awful hack for bold + faint
                int offset = str[3]==017?16:str[4]==017?17:0;
                printf ("%s%s%s%s""%.*s%s%s""%s%s%s%s",
                        "\033[1m", invert?"\033[7m":"", grey_bg?"\033[100m":"", blink?"\033[5m":"",
                        offset, str, bold?"\033[1m":"", str+offset,
                        blink?"\033[25m":"", grey_bg?"\033[49m":"", invert?"\033[27m":"","\033[22m");
                return;
        }
        printf ("%s%s%s%s%s%s%s%s%s",
                bold?"\033[1m":"", invert?"\033[7m":"", grey_bg?"\033[100m":"", blink?"\033[5m":"",
                str,
                blink?"\033[25m":"", grey_bg?"\033[49m":"", invert?"\033[27m":"",bold?"\033[22m":"");
}
void print_table(const struct cursor* active, const struct cursor* inactive) {
        printf("\033[2J\033[H"); /* clear screen, reset cursor */
#ifdef KLONDIKE
        /* print stock, waste and foundation: */
        for (int line = 0; line < op.s->height; line++) {
                /* stock: */
                print_hi (active->pile == STOCK, inactive->pile == STOCK, 1, 0, (
                        (f.w < f.z-1)?op.s->facedown
                        :op.s->placeholder)[line]);
                /* waste: */
                int do_blink = hls(f.s[f.w], f.h); //xxx: unnecessarily recalculating
                print_hi (active->pile == WASTE, inactive->pile == WASTE, 1, do_blink, (
                        /* NOTE: cast, because f.w sometimes is (short)-1 !? */
                        ((short)f.w >= 0)?op.s->card[f.s[f.w]]
                        :op.s->placeholder)[line]);
                printf ("%s", op.s->card[NO_CARD][line]); /* spacer */
                /* foundation: */
                for (int pile = 0; pile < NUM_SUITS; pile++) {
                        int card = find_top(f.f[pile]);
                        print_hi (active->pile==FOUNDATION && active->opt==pile,
                                inactive->pile==FOUNDATION && (
                                        /* cursor addr.     || direct addr.   */
                                        inactive->opt==pile || inactive->opt < 0
                                ), !!f.f[pile][0], 0,
                                (card < 0)?op.s->foundation[line]
                                :op.s->card[f.f[pile][card]][line]);
                }
                printf("\n");
        }
        printf("\n");
#elif defined SPIDER
        int fdone; for (fdone = NUM_DECKS*NUM_SUITS; fdone; fdone--)
                if (f.f[fdone-1][RANK_K]) break;  /*number of completed stacks*/
        int spacer_from = f.z?(f.z/10-1) * op.s->halfwidth[0] + op.s->width:0;
        int spacer_to   = NUM_PILES*op.s->width -
                ((fdone?(fdone-1) * op.s->halfwidth[1]:0)+op.s->width);
        for (int line = 0; line < op.s->height; line++) {
                /* available stock: */
                for (int i = f.z/10; i; i--) {
                        if (i==1) printf ("%s", op.s->facedown[line]);
                        else      printf ("%s", op.s->halfstack[line]);
                }
                /* spacer: */
                for (int i = spacer_from; i < spacer_to; i++) printf (" ");
                /* foundation (overlapping): */
                for (int i = NUM_DECKS*NUM_SUITS-1, half = 0; i >= 0; i--) {
                        int overlap = half? op.s->halfcard[line]: 0;
                        if (f.f[i][RANK_K]) printf ("%.*s", op.s->halfwidth[2],
                                op.s->card[f.f[i][RANK_K]][line]+overlap),
                                half++;
                }
                printf("\n");
        }
        printf("\n");
#elif defined FREECELL
        /* print open cells, foundation: */
        for (int line = 0; line < op.s->height; line++) {
                for (int pile = 0; pile < NUM_CELLS; pile++) {
                        int do_blink = hls(f.s[pile], f.h);
                        print_hi (active->pile==STOCK && active->opt==pile,
                                inactive->pile==STOCK && (
                                        /* cursor addr.     || direct addr.   */
                                        inactive->opt==pile || inactive->opt < 0
                                ), !!f.s[pile], do_blink,
                                ((f.s[pile])?op.s->card[f.s[pile]]
                                :op.s->placeholder)[line]);
                }
                for (int pile = 0; pile < NUM_SUITS; pile++) {
                        int card = find_top(f.f[pile]);
                        print_hi (active->pile==FOUNDATION && active->opt==pile,
                                inactive->pile==FOUNDATION && (
                                        /* cursor addr.     || direct addr.   */
                                        inactive->opt==pile || inactive->opt < 0
                                ), !!f.f[pile][0], 0,
                                (card < 0)?op.s->foundation[line]
                                :op.s->card[f.f[pile][card]][line]);
                }
                printf("\n");
        }
        printf("\n");
#endif
#ifdef KLONDIKE
#define DO_HI(cursor) (cursor->pile == pile && (movable || empty))
#define TOP_HI(c) 1 /* can't select partial stacks in KLONDIKE */
#elif defined SPIDER || defined FREECELL
        int offset[NUM_PILES]={0}; /* first card to highlight */
#  ifdef FREECELL
        int bottom[NUM_PILES]; /* first movable card */
        for (int i=0; i<NUM_PILES; i++)
                bottom[i] = find_top(f.t[i]) - max_move(i,-1);
#  endif
#define DO_HI(cursor) (cursor->pile == pile && (movable || empty) \
        && offset[pile] >= cursor->opt)
#define TOP_HI(cursor) (cursor->pile == pile && movable \
        && offset[pile] == cursor->opt)
#endif
        /* print tableu piles: */
        int row[NUM_PILES] = {0};
        int line[NUM_PILES]= {0};
        int label[NUM_PILES]={0};
        int line_had_card;
        int did_placeholders = 0;
        do {
                line_had_card = 0;
                for (int pile = 0; pile < NUM_PILES; pile++) {
                        card_t card = f.t[pile][row[pile]];
                        card_t next = f.t[pile][row[pile]+1];
                        int movable = is_movable(f.t[pile], row[pile]);
                        int do_blink = hls(card, f.h);
#ifdef FREECELL
                        if(row[pile] <= bottom[pile]) movable = 0;
#endif
                        int empty   = !card && row[pile] == 0;

                        print_hi (DO_HI(active), DO_HI(inactive), movable, do_blink, (
                                (!card && row[pile] == 0)?op.s->placeholder
                                :(card<0)?op.s->facedown
                                :op.s->card[card]
                                )[line[pile]]);

                        int extreme_overlap = ( 3  /* spacer, labels, status */
                                + 2 * op.s->height /* stock, top tableu card */
                                + find_top(f.t[pile]) * op.s->overlap) >op.w[0];
                        /* normal overlap: */
                        if (++line[pile] >= (next?op.s->overlap:op.s->height)
                        /* extreme overlap on closed cards: */
                        || (extreme_overlap &&
                            line[pile] >= 1 &&
                            f.t[pile][row[pile]] < 0 &&
                            f.t[pile][row[pile]+1] <0)
                        /* extreme overlap on sequences: */
                        || (extreme_overlap &&
                            !TOP_HI(active) && /*always show top selected card*/
                            line[pile] >= 1 && row[pile] > 0 &&
                            f.t[pile][row[pile]-1] > NO_CARD &&
                            is_consecutive (f.t[pile], row[pile]) &&
                            is_consecutive (f.t[pile], row[pile]-1) &&
                            f.t[pile][row[pile]+1] != NO_CARD)
                        ) {
                                line[pile]=0;
                                row[pile]++;
#if defined SPIDER || defined FREECELL
                                if (movable) offset[pile]++;
#endif
                        }
                        /* tableu labels: */
                        if(!card && !label[pile] && row[pile]>0&&line[pile]>0) {
                                label[pile] = 1;
                                printf ("\b\b%d ", (pile+1) % 10); //XXX: hack
                        }
                        line_had_card |= !!card;
                        did_placeholders |= row[pile] > 0;
                }
                printf ("\n");
        } while (line_had_card || !did_placeholders);
}

void visbell (void) {
        if (!op.v) return;
        printf ("\033[?5h"); fflush (stdout);
        usleep (100000);
        printf ("\033[?5l"); fflush (stdout);
}
void win_anim(void) {
        printf ("\033[?25l"); /* hide cursor */
        for (;;) {
                /* set cursor to random location */
                int row = 1+rand()%(1+op.w[0]-op.s->height);
                int col = 1+rand()%(1+op.w[1]-op.s->width);

                /* draw random card */
                int face = 1 + rand() % 52;
                for (int l = 0; l < op.s->height; l++) {
                        printf ("\033[%d;%dH", row+l, col);
                        printf ("%s", op.s->card[face][l]);
                }
                fflush (stdout);

                /* exit on keypress */
                struct pollfd p = {STDIN_FILENO, POLLIN, 0};
                if (poll (&p, 1, 80)) goto fin;
        }
fin:
        printf ("\033[?25h"); /* show cursor */
        return;
}
//}}}

// undo logic {{{
void undo_push (int _f, int t, int n, int o) {
        struct undo* new = malloc(sizeof(struct undo));
        new->f = _f;
        new->t = t;
        new->n = n;
        new->o = o;
        new->prev = f.u;
        new->next = NULL;
        f.u->next = new;
        f.u = f.u->next;
}
void undo_pop (struct undo* u) {
        if (u == &undo_sentinel) return;

#ifdef KLONDIKE
        if (u->f == FOUNDATION) {
                /* foundation -> tableu */
                int top_f = find_top(f.f[u->n]);
                int top_t = find_top(f.t[u->t]);
                f.f[u->n][top_f+1] = f.t[u->t][top_t];
                f.t[u->t][top_t] = NO_CARD;
        } else if (u->f == WASTE && u->t == FOUNDATION) {
                /* waste -> foundation */
                /* split u->n into wst and fnd: */
                int wst = u->n & 0xffff;
                int fnd = u->n >> 16;
                /* move stock cards one position up to make room: */
                for (int i = f.z; i >= wst; i--) f.s[i+1] = f.s[i];
                /* move one card from foundation to waste: */
                int top = find_top(f.f[fnd]);
                f.s[wst] = f.f[fnd][top];
                f.f[fnd][top] = NO_CARD;
                f.z++;
                f.w++;
        } else if (u->f == WASTE) {
                /* waste -> tableu */
                /* move stock cards one position up to make room: */
                for (int i = f.z-1; i >= u->n; i--) f.s[i+1] = f.s[i];
                /* move one card from tableu to waste: */
                int top = find_top(f.t[u->t]);
                f.s[u->n] = f.t[u->t][top];
                f.t[u->t][top] = NO_CARD;
                f.z++;
                f.w++;
        } else if (u->t == FOUNDATION) {
                /* tableu -> foundation */
                int top_f = find_top(f.t[u->f]);
                int top_t = find_top(f.f[u->n]);
                /* close topcard if previous action caused turn_over(): */
                if (u->o) f.t[u->f][top_f] *= -1;
                /* move one card from foundation to tableu: */
                f.t[u->f][top_f+1] = f.f[u->n][top_t];
                f.f[u->n][top_t] = NO_CARD;
        } else {
                /* tableu -> tableu */
                int top_f = find_top(f.t[u->f]);
                int top_t = find_top(f.t[u->t]);
                /* close topcard if previous action caused turn_over(): */
                if (u->o) f.t[u->f][top_f] *= -1;
                /* move n cards from tableu[f] to tableu[t]: */
                for (int i = 0; i < u->n; i++) {
                        f.t[u->f][top_f+u->n-i] = f.t[u->t][top_t-i];
                        f.t[u->t][top_t-i] = NO_CARD;
                }
        }
#elif defined SPIDER
        if (u->f == STOCK) {
                /* stock -> tableu */
                /*remove a card from each pile and put it back onto the stock:*/
                for (int pile = NUM_PILES-1; pile >= 0; pile--) {
                        int top = find_top(f.t[pile]);
                        f.s[f.z++] = f.t[pile][top];
                        f.t[pile][top] = NO_CARD;
                }
        } else if (u->t == FOUNDATION) {
                /* tableu -> foundation */
                int top = find_top(f.t[u->f]);
                /* close topcard if previous action caused turn_over(): */
                if (u->o) f.t[u->f][top] *= -1;
                /* append cards from foundation to tableu */
                for (int i = RANK_K; i >= RANK_A; i--) {
                        f.t[u->f][++top] = f.f[u->n][i];
                        f.f[u->n][i] = NO_CARD;
                }
                f.w--; /* decrement complete-foundation-counter */

        } else {
                /* tableu -> tableu */
                int top_f = find_top(f.t[u->f]);
                int top_t = find_top(f.t[u->t]);
                /* close topcard if previous action caused turn_over(): */
                if (u->o) f.t[u->f][top_f] *= -1;
                /* move n cards from tableu[f] to tableu[t]: */
                for (int i = 0; i < u->n; i++) {
                        f.t[u->f][top_f+u->n-i] = f.t[u->t][top_t-i];
                        f.t[u->t][top_t-i] = NO_CARD;
                }
        }
#elif defined FREECELL
        /*NOTE: if from and to are both stock/foundation, opt = from | to<<16 */
        if (u->f == STOCK && u->t == FOUNDATION) {
                /* free cells -> foundation */
                /* split u->n into cll and fnd: */
                int cll = u->n & 0xffff;
                int fnd = u->n >> 16;
                /* move one card from foundation to free cell: */
                int top = find_top(f.f[fnd]);
                f.s[cll] = f.f[fnd][top];
                f.f[fnd][top] = NO_CARD;
                f.w |= 1<<cll; /* mark cell as occupied */
        } else if (u->f == STOCK) {
                /* free cells -> cascade */
                int top_t = find_top(f.t[u->t]);
                f.s[u->n] = f.t[u->t][top_t];
                f.t[u->t][top_t] = NO_CARD;
                f.w |= 1<<u->n; /* mark cell as occupied */
        } else if (u->f == FOUNDATION && u->t == STOCK) {
                /* foundation -> free cells */
                /* split u->n into cll and fnd: */
                int cll = u->n >> 16;
                int fnd = u->n & 0xffff;
                /* move 1 card from free cell to foundation: */
                int top_f = find_top(f.f[fnd]);
                f.f[fnd][top_f+1] = f.s[cll];
                f.s[cll] = NO_CARD;
                f.w &= ~(1<<cll); /* mark cell as free */
        } else if (u->f == FOUNDATION) {
                /* foundation -> cascade */
                int top_f = find_top(f.f[u->n]);
                int top_t = find_top(f.t[u->t]);
                f.f[u->n][top_f+1] = f.t[u->t][top_t];
                f.t[u->t][top_t] = NO_CARD;
        } else if (u->t == STOCK) {
                /* cascade -> free cells */
                int top_f = find_top(f.t[u->f]);
                f.t[u->f][top_f+1] = f.s[u->n];
                f.s[u->n] = NO_CARD;
                f.w &= ~(1<<u->n); /* mark cell as free */
        } else if (u->t == FOUNDATION) {
                /* cascade -> foundation */
                int top_f = find_top(f.t[u->f]);
                int top_t = find_top(f.f[u->n]);
                /* move one card from foundation to cascade: */
                f.t[u->f][top_f+1] = f.f[u->n][top_t];
                f.f[u->n][top_t] = NO_CARD;
        } else {
                /* cascade -> cascade */
                int top_f = find_top(f.t[u->f]);
                int top_t = find_top(f.t[u->t]);
                /* move n cards from tableu[f] to tableu[t]: */
                for (int i = 0; i < u->n; i++) {
                        f.t[u->f][top_f+u->n-i] = f.t[u->t][top_t-i];
                        f.t[u->t][top_t-i] = NO_CARD;
                }
        }
#endif

        void* old = f.u;
        f.u = f.u->prev;
        free(old);
}
void free_undo (struct undo* u) {
        while (u && u != &undo_sentinel) {
                void* old = u;
                u = u->prev;
                free (old);
        }
}
//}}}

// initialization stuff {{{
void screen_setup (int enable) {
        if (enable) {
                raw_mode(1);
                printf ("\033[s\033[?47h"); /* save cursor, alternate screen */
                printf ("\033[H\033[J"); /* reset cursor, clear screen */
                printf ("\033[?1000h"); /* enable mouse */
        } else {
                printf ("\033[?1000l"); /* disable mouse */
                printf ("\033[?47l\033[u"); /* primary screen, restore cursor */
                raw_mode(0);
        }
}

void raw_mode(int enable) {
        static struct termios saved_term_mode;
        struct termios raw_term_mode;

        if (enable) {
                if (saved_term_mode.c_lflag == 0)/*don't overwrite stored mode*/
                        tcgetattr(STDIN_FILENO, &saved_term_mode);
                raw_term_mode = saved_term_mode;
                raw_term_mode.c_lflag &= ~(ICANON | ECHO);
                raw_term_mode.c_cc[VMIN] = 1 ;
                raw_term_mode.c_cc[VTIME] = 0;
                tcsetattr(STDIN_FILENO, TCSAFLUSH, &raw_term_mode);
        } else {
                tcsetattr(STDIN_FILENO, TCSAFLUSH, &saved_term_mode);
        }
}

void signal_handler (int signum) {
        struct winsize w;
        switch (signum) {
        case SIGTSTP:
                screen_setup(0);
                signal(SIGTSTP, SIG_DFL); /* NOTE: assumes SysV semantics! */
                raise(SIGTSTP);
                break;
        case SIGCONT:
                screen_setup(1);
                print_table(NO_HI, NO_HI);
                break;
        case SIGINT: //TODO: don't exit; just warn like vim does
                exit(128+SIGINT);
        case SIGWINCH:
                ioctl(STDOUT_FILENO, TIOCGWINSZ, &w);
                op.w[0] = w.ws_row;
                op.w[1] = w.ws_col;
                break;
        }
}
void signal_setup(void) {
        struct sigaction saction;

        saction.sa_handler = signal_handler;
        sigemptyset(&saction.sa_mask);
        saction.sa_flags = 0;
        if (sigaction(SIGTSTP, &saction, NULL) < 0) {
                perror ("SIGTSTP");
                exit (1);
        }
        if (sigaction(SIGCONT, &saction, NULL) < 0) {
                perror ("SIGCONT");
                exit (1);
        }
        if (sigaction(SIGINT, &saction, NULL) < 0) {
                perror ("SIGINT");
                exit (1);
        }
        if (sigaction(SIGWINCH, &saction, NULL) < 0) {
                perror ("SIGWINCH");
                exit (1);
        }
}
//}}}

//vim: foldmethod=marker